Fuse link



Feb. 14, 1933. A. a. STEINMAYER FUSE LINK Filed Dec. 26, 1929 3mm I ly long,

Patented Feb. 14, 1933 UNITED STATES PATENT OFFICE.

ALWIN G. STEINMAYER,'OF MILWAUKEE, WISCONSIN, ASSIGNOR TO LINE MATERIAL COMPANY, OF SOUTH MILWAUKEE, WISCONSIN, A

CORPORATION OF DELAWARE FUSE LINK Application filed December 26, 1929. Serial No. 416,325.

This invention relates to fuse links. In fuse links as heretofore constructed, it

has been found extremely difiicult to make a v; amperage fuse link which is mechanically strong form capacity.

When it is considered that in the high voltage circuits the fuse links have to be relativeit will be seen that the small diame- 10 ter of low amperage fuses renders them parsulating tubing,

length of the fuse li 5 is a slow carbonization which takes place 5 capacity other than that which frequently finally results in burning through the fuse cartridge.

In addition to the defects noted above, it has been the common practice to solder one end at least of the fuse link to a terminal clip or contact member. This process of soldering usually reduces the section of the fuse link immediately adjacent the clip and thus varies the capacity of the fuse and makes the for which the fuse is intended. In addition to this, certain chemical changes take place adjacent the soldered joint due to the soldering. The heat and the chemical nature of the solder fre quently varies the chemical nature of the fuse link. Thus there is very frequently a change in capacity of the fuse from that at which it was intended to melt.

This invention is designed to overcome the defects noted above and objects of this invention are to provide a novel form of fuse link which may be made in any size desired, even in the very small or low amperage sizes, and

which is reinforced at a portion of its length, where it is of reduced cross section to meand which also may be made of a uni-' fuse to clear too rapidly,

chanically protect the fuse at its most delicate portion.

A further object is to provide a fuse link which, although reinforced at the portion of reduced cross section, permits the ready inspection of the reinforced part, so that it is easy to determine the condition of the fuse although the fuse is reinforced.

Further objects are to provide a fuse link which has a reduced portion held in a me chanically slack condition by insulating reinforcing means which relieves the reduced portion of any mechanical strain, which is so made that no choking is produced when the fuse blows, and which protects the cartridge from intense heat at the instant the fuse melts.

Further objects are to provide a fuse link which is equipped with a contact clip, which does not require soldering to the contact clip,-

but which, instead, is so made that an extensive contact area is assured by mechanical means without damage to the fuse link.

Further objects are to provide a fuse link which is so made that it will have a reduced portion precisely determining the value of the current at which the fuse will blow, and which is of sturdy construction throughout its entire length, although the fuse link may be of small capacity.

Further objects are to provide a fuse link in which the of one material and shape, and in which the reduced portion may be made of a different shape and of the same or of a different material from the major portion.

structicn which will be free from radio interference after the fuse blows, and which is so made that the reduced portion will be completely destroyed under all conditions, and which, even if link is not destro ed, wi nevertheless provide a wide brea or spacing between any remaining portion.

An embodiment of the invention is shown in the accompanying drawing, in which:

Figure 1 is an elevation of the fuse cartridge with parts in section showing the fuse link in place.

major portions may be made Further objects are to provide a fuse conthe majorlportion of the fuse Figure -2 is a fragmentary view of the fuse link removed from the cartridge and drawn to an enlarged scale with a part of the reinforcing means sectioned oif.

Figure 3 is a sectional view on the line 3-3 of the Figure 2.

Figure 4 is a sectional view on the line 4 -4 of Figure 2.

Figure 5 is a side elevation of a modified form of construction particularly directed to the terminal clip or contact clip, such view being partly in section.

Figure 6 is a plane view, partly broken away, of the structure shown in Figure 5.

Referring to the drawing, it will be seen that the fuse structure comprises an elongated body portion or fuse cartridge 1 of insulating material. This cartridge carries an upper metal contact member 2 provided with a transversely extending upper portion or wall having an aperture 3 therethrough. The upper end of the contact member 2 is threaded and receives the threaded clamping cap 51. The lower portion of the cartridge is provided with a lower contact member 5 having a tapered portion 6 against which the fuse link may be clamped by means of the clamping nut 7. Preferably the threaded portion or shoulder 8 of the lower contact member is provided with a slot 9 through which the end of the fuse link may extend as indicated in Figure 1.

It is to be distinctly understood that the expressions upper and lower are used merely for simplicity of description and to avoid needless repetition, as obviously the fuse could be used in other positions from that shown without departing from the spirit of this invention. Therefore these expressions upper and lowerare not to be'interpreted as specifically limiting expressions.

The fuse link comprises two major portions, a lower portion 10 and an upper portion 11. The upper portion is preferably materially shorter than the lower portion so as to correctly position the reduced part in the upper portion of the fuse cartridge as shown in Figure 1.

The two major portions 10 and 11 are each formed of a flexible metal strip preferably of fusible material, and these sections or por tions have their ends spaced apart as shown most clearly in Figure 2. A pair of fiber reinforcing strips 12 are used to mechanically join the major portions of the fuse link and to hold opposedeends ofthese portions in spaced relation. A fusible element 13 is interposed bet-ween the spaced ends of the portions 10 and 11 and joins such portions. This fusible element constitutes an intermediate portion in the fuse link of reduced cross section, and it may be made of the same or of diiferent material from that of the portions 10 and 11. This portion 13, as will be seen very readily from Figure 2, is held in a slack and insure extensive and adequate condition by the insulating fiber strips 12, so that there is no chance for mechanical strain to be applied to the reduced portion 13 even if the fuse link is flexed at the fiber strips.

Preferably the fiber strips 12 are positioned on opposite sides of the portion 13 and are secured in place by rivets 14 extending through the fiber strips and through the portions 10 and 11. These rivets also preferably have the member 13 wrapped around them or in contact with them, as shown in Figure 2. However, when the rivets are drawn up in the process of riveting, they Will firmly bind the portion 13 against the portions 10 and 11 contact between such portions.

It is, of course, to be understood that it is within the province of this invention to use a single fiber strip if desired, unless otherwise specifically claimed.

It will be noted from the construction thus far outlined that a flexible fuse link has been provided which is equipped with a reduced section mechanically protected. It is to be noted, however, that this reduced section may be very readily inspected, as is apparent from Figure 1, for the fiber strips form in efiect a housing for this reduced portion which is openat its longitudinal edges.

It is thus apparent that no testing of this fuse link is required to ascertain whether or not it is continuous throughout, but that this condition may be readily ascertained by a simple inspection.

It has been found that when fuse links are soldered to the terminal contact clips, frequently the section of the fuse'link adjacent the clip is altered and, in addition, it is frequently found that the chemical nature of the fuse link has been changed adjacent the soldered portion. This produces an uncertainty or variation in fuses which require soldering.

This invention overcomes the difiiculty noted above as no soldering is required in tll e joining of the fuse link to the terminal 0 1p.

One form of the invention employs a metal terminal clip 15 which is provided with a central aperture 16 through which the portion 11 of the fuse link is threaded. The upper projecting portion is then folded across the upper face of the contact clip 15 as shown in Figures 3 and 4 and its end passed back through the opening 16 and clinched as indicated at 17. Also either one or both of the 15 folded or looped ends may be clinched around an edge of the contact clip. For instance, the portion 18 has been shown as clinched around the edge of the clip 15 in Figures 3 and 4. 1

A further and a preferred form of contact clip is shown in Figures 5 and 6. The contact clip consists of an upper, disc like member 19 and a lower disc like member 20, the lower member being provided with a slot 21. l

-either vided by this invention which may the major portions of the fuse lin greatly overloaded as,

10 19 and the lower disc 20 of the clip, the body of the member 22 extendin downwardly. throu h the slot 21. Obvious it is an extreme y easy matter to insert the upper memher 22 through the slot 21 while the discs are partially or wholly opened out. Thereafter t e upper disc is folded down into the position shown in Figures 5 and 6.

minal clips or contact clips a very extensive contact is secured between the terminal or contact clip and the fuse link.

In addition to this, when the fuse, link is positioned within the fuse cartridge with the cap v4 and the upper contact member, it be seen that the fuse link is tightly held, and an extensive electrical contact is secured.

.It will be seen that a ve simple and eminently practical fuse link has been proin any desired capacity even for ve loy amperage and for high voltage. .Furt er, it will be noted that the reduce po forcin insulating ortion, so that it is free from t e chance of amage or from mechanical strain.

It is to be noted also that the s acing of is such that a wide separation is obtained even when only the reduced portion 13 is melted as, for instance, when the fuse blows due to overload condition. Consequently, there is no chance of radio interference even under these most disadvantageous conditions. On the other hand, if the flue should be suddenly and for instance, under short circuit conditions, the entire fusible element, including the major portions" and the reduced portions, would be destroyed, and, consequently, there would be no chance even under the condition of extreme load of the establishing of an arc in the fuse car- 55 tridge, as an extremely wide separation would then be obtained.

It will be seen that a very sim 1e and relatively cheap and eminently 'relia le fuse link has been provided by this invention.

Although this invention has been described in considerable detail, it. is to be understood that such description is intended as illustrative rather than limiting, as the invention may be variously embodied and is to be inter-- preted as claimed.

4 chanical terminal clip clamped between the clamlilnfi be made their longitudinal rtion is mechanically protected from all damage and y 35 also is held in a slack condition by the rein- I claim:

1. A flexible fuse link adapted to be bad ily threaded into a. fuse cartri e comprising a composite-fuse consisting of two spaced fusible strips forming the ma'or' portion of the fuse link, an intermediate sible portion electrically joining said spaced of lesser cross section than said spaced portions, and an insulating member joining said spaced fusible portions and holding said intermediate fusible portion in a slack condi-,

tion.

2. 'A fuse link comprising-a pair of elongated fusible members of flexible fusible metal, having their ends spaced apart, a nonfragile insulating mediate fusible member held in a slack condition by said insulating member and mey clamped ateach end to the corresponding end of said first mentioned fusible members.

3. A fuse link comprising a pair of elon; gated fusible members of flexible fusible metal having spaced ends, an intermediate fusible member electrically joining the spaced ends of said first mentioned fusible members, a pair of insulatin strips enclosing between them said interme iate fusible member, said insulating strips leaving an open space along edges, and means mechanically clamping the-ends of said insulatin strips and the ends of said intermediate and first mentioned fusible members together.

' 4. A fuse link com risin an elongated fusible element of rib n-li e flexible conducting material, a contact clip having an upper plate and a lower plate oined by an intermediate offset portion, the lower plate having an elongated slot therethrough and ALWIN G. STEINMAYER.

portions and member joining the spaced ends of said fuslble members, and an inter- It will be seen thatin both forms of terone end threaded 

